Nightly News | December 18, 2013
>>> good evening. it's been a long time and it's a far cry from the speech by president john f. kennedy challenging americans to conquer space, which we did by the way in short order. these days our astronauts ride to space on board russian spacecraft and make up part of the crew on the international space station . it is right now carrying six adults orbiting the earth every 90 minutes at 17,000 miles an hour. there is a problem on board. one of two crucial pumps has blown. they are running on backup. it will take three space walks to fix it. the problem is during the last space walk an astronaut's helmet filled with water. so today nasa said the space walking astronauts will wear snorkels inside their helmets along with absorbent pads so they won't drown. nbc's tom costello is in washington with more. tom, just when you think you've heard it all.
>> reporter: it's a just in case move. nasa engineers think they know why the astronaut's helmet filled with water last july. it has to do with tiny particle residues clogging the suit's water lines. they have cut rubber tubing to make sure and have snorkels for both astronauts. on board the international space station , astronauts were today inspecting the space suits they will be wearing for saturday's repair mission.
>> there is a small, small, small particle --
>> reporter: one of of the suits will be the one worn by the italian astronaut last july when he nearly drowned after his helmet suddenly filled with water.
>> water is in his eyes now and seems to be increasing. we are going to terminate eva case for ev-2.
>> reporter: he later talked about the scare.
>> i started going back to the airlock.
>> reporter: fellow astronauts got him inside and removed the helmet just as the water prevented him from talking.
>> about three pounds of water, i would say. that was the end of it.
>> reporter: it was a very close call . since then, no space walks or evas. now two astronauts are going back out on an urgent mission.
>> we understand first eva the 21st, the 23rd and on christmas day if we with need it.
>> reporter: the movie "gravity" helped fuel the public fascination with the real space station, the size of a football field . now the real crew must remove and replace one of two 780-pound ammonia pumps that keep the station cool. it's been down for a week forcing them to conserve power. nasa spent months inspecting the suit and replacing internal components. they think it is fixed. but just in case nasa turned to the in-house ingenuity made famous in apollo xiii we have to find a way to make this fit into the hole for this using nothing but that.
>> reporter: on saturday, both astronauts will wear an absorbent pad in the back of their helmets and a snorkel cut from water tubing.
>> this is a last resort that if water is encroaching your face the crew member can lean down and use this to breathe.
>> reporter: an urgent mission 230 miles above the earth, and a lingering fear after a very close call . each space walk will last six and a half hours, replacing the failed cooling pump is urgent. if the second pump goeses down they would have to abandon the station. they will get under way saturday morning with two more walks scheduled for monday and then wednesday. brian?
>> tom costello starting us off from washington on matters in space. tom, thanks.